Florence Welch is a powerful singer and a bit of a style icon. But she doesn't seem like a rabble-rouser -- until you get to know her.

She took the stage Saturday night at the Woodlands Pavilion in a flowing, backless gown buttoned up to her neck. It looked like a choir robe against the stained-glass imagery on the stage backdrop. Her red hair, which gave her problems later, was pinned up in a messy bun.

She jerked and hunched her way through the first few songs ("Only If for a Night," "Cosmic Love, "Between Two Lungs"), often skipping or running from one side of the stage to another. Her band, the Machine, provided a sturdy framework (including a harp). She grinned sheepishly at the enthusiastic crowd between songs. (No lawn seating was sold for the show.)

Then, things got a little crazy.

"I know this is a seated venue, but we can subvert the venue," she shouted before launching into "Rabbit Heart (Raise It Up)." "Lift up your brothers! Lift up your sisters!"

Several people were immediately hoisted onto shoulders, a security no-no at most shows. But when the headliner commands, fans listen. Welch then jumped offstage and raced around the venue, security dashing madly behind her.

She had another request once back onstage, asking everyone to shake hands, embrace, hug or make out with the person next to them.

"We're really looking for you to express yourself in this next song," she said. The thundering disco pulse of "Spectrum" fully loosened Welch up, and she careened across the stage, pausing after to fix her tousled hair.

"This is the bit where I seem like a slightly deranged old lady," she said before disappearing backstage for a few seconds. "It's a fine line."

Welch's appeal is in those contrasts. Her towering, confident voice and awestruck banter. (She seemed near tears when discussing how welcoming America has been.) Her regal first impression and mischievous personality. The darkness and light in her music. Most every moment was entertaining.

"Leave My Body," simmered with pain and soul;" and the ominous "Seven Devils" was made all the spookier by a fierce downpour of rain and flashes of lightning.

The biggest reactions, of course, came during "Shake It Out" and "Dog Days Are Over," triumphant anthems of pop perseverance. Welch's immensely likable presence and voice, however, seem destined to make her more than a two-hit wonder.